Human-implantable-neurostimulator user interface having multiple levels of abstraction

ABSTRACT

A programming-device user interface may include multiple levels of abstraction for programming treatment settings. A stimulation zone-programming interface may be at a highest level of abstraction and may include idealized stimulation zones. A field strength-programming interface may be at a middle level of abstraction and may include electromagnetic field-strength patterns generated by the stimulation zones, and/or electrode settings, and a depiction of how the electromagnetic fields interact with each other. An electrode-programming interface may be at a lowest level of abstraction and may depict treatment settings at an electrodes-view level. These interfaces may include a display of a stimulatable area of the patient&#39;s body. The display may include a depiction of leads and/or the underlying physiology, such as a depiction of a portion of a spine. Algorithms map treatment settings from one level of abstraction to settings at one or more other levels of abstraction.

This application is a continuation of application Ser. No. 10/295,752,filed on Nov. 15, 2002, the entire content of which is incorporatedherein by reference.

TECHNICAL FIELD

The invention relates generally to a medical-device user interface andmore particularly to such a user interface having multiple levels ofabstraction.

BACKGROUND OF THE INVENTION

Medical devices are commonly used today to treat patients suffering fromvarious ailments. Implantable medical devices can be used to treatconditions such as pain, incontinence, movement disorders, such asepilepsy and Parkinson's disease, and sleep apnea. Additionally, use ofmedical devices appears promising to treat a variety of physiological,psychological, and emotional conditions.

One type of medical device is an Implantable Pulse Generator (IPG). AnIPG may be implanted within a patient's body. The IPG may then generateand deliver electrical stimulation signals to influence selected neuraltissue to treat a particular ailment. The stimulation sites may includethe spinal cord, brain, body muscles, peripheral nerves, or other sitesselected by a physician. For example, in the case of pain, electricalimpulses may be directed to particular nerves associated with specificsites where the patient is feeling pain. Neurostimulation can givepatients effective pain relief and can reduce or eliminate the need forrepeat surgeries and pain medications.

An IPG system may include an implantable pulse generator, a programmingdevice, and at least one electrical lead. The IPG may be powered by aninternal source such as a rechargeable or non-rechargeable battery or byan external source such as a radio frequency transmitter. The IPGgenerates and sends precise, electrical pulses to the stimulation areato provide the desired treatment therapy.

The programming device may be an external device that allows a physicianand/or patient to communicate with the IPG. A physician may create andstore stimulation therapy programs to be administered to the patient bythe IPG. The programming device may communicate bi-directionally withthe IPG, via RF telemetry signals.

Programming of IPGs has traditionally been done from the hardware levelup. For instance, setting amplitudes for particular electrodes thatwould result in some type of stimulation pattern. Conventionalprogramming-device user interfaces typically do not display astimulation pattern generated by particular electrode settings.Physicians may not be comfortable thinking about stimulation in terms ofelectrodes programmed as cathodes and anodes. Further, when there aremore than one or two cathode/anode pairs, it becomes relativelydifficult to think about how the various electromagnetic fields mayinteract. There are transverse elements where dipoles affect otherdipoles, and the like.

Further, a physician using a conventional user interface to try tooptimize therapy settings typically a programming device in one hand andan x-ray or fluoroscopy of the intended stimulation area in the otherhand. The x-ray or fluoroscopy shows where the leads are relative to theintended stimulation site, such as the patient's spine. A physiciantypically knows where nerves come out of a patient's spine and lead toparticular areas of the patient's body. So, to treat pain, for instance,the physician is typically trying to arrange the electrodes near thoselocations of the spine. Accordingly, an interface that shows where leadsare placed within the patient's body and that presents a view ofstimulation patterns generated by various electrodes settings would bedesirable.

SUMMARY OF THE INVENTION

In accordance with an illustrative embodiment of the invention and asdescribed in more detail below, a programming-device user interface mayinclude multiple levels of abstraction. A highest level of abstraction,referred to as a stimulation zone-programming interface, may showidealized stimulation zones. A middle level of abstraction, referred toas a field strength-programming interface, may show electromagneticfields generated by the stimulation zones, and/or electrode settings,and how these electromagnetic fields interact with each other. A lowestlevel of abstraction, referred to as an electrode-programming interface,may depict treatment settings at an electrodes-view level. Theseinterfaces may include a display of a stimulatable area of the patient'sbody. The various forms of this type of display may be referred toherein as a stimulation-zones view, a field-strength view, and anelectrodes view, respectively.

A stimulation zone-programming interface, in accordance with anillustrative embodiment of the invention, is relatively simple tointeract with and is at a relatively high level of abstraction. Thestimulation zone-programming interface lets a user work abstractly withidealized stimulation zones. A user may add a stimulation zone and maymove the stimulation zone to a desired location. The user may adjust thestimulation zone's parameters, such as its intensity, its pulse width,and its rate.

A display area of the stimulation zone-programming user interface mayrepresent a stimulatable area within the patient's body, which is anarea in which implanted stimulation leads are able to producestimulation. Before creating idealized stimulation zones, a user mayenter information specifying where, within a patient's body, one or moreleads are placed, such as where the leads are located relative tospecific portions of the patient's spine. Idealized stimulation zonesmay then be placed relative to placement of the leads.

An image of the underlying physiology of the stimulatable area, such asa portion of the patient's spine, may be displayed based on thelead-location information. The physician may then place stimulationzones relative to the depiction of the stimulatable area's underlyingphysiology, such as a depiction of the patient's spine.

After programming a first stimulation zone, the physician may add one ormore additional stimulation zones and may move the stimulation zones todesired locations. The stimulation zones may be placed in accordancewith knowledge of where the nerves, which lead to the arms and legs,come out of the spine. Stimulation zones may be selected, moved, andremoved as desired.

Stimulation zones may be placed at predefined locations within thedisplay area, such as at an intersection of a horizontal grid line and avertical grid line. Intersections of this type may correspond toelectrode locations and locations substantially centrally locatedbetween an electrode on a first lead and an electrode on a second lead.

A field strength-programming interface, in accordance with anillustrative embodiment of the invention, may be at a level ofabstraction lower than the stimulation zone-programming interface and ata level higher than the electrode-programming interface. For a user whois comfortable thinking about electromagnetic fields directly, the usermay paint on the user interface what the user wants the field pattern tolook like. Darker colors may be used to represent more intensity, forinstance.

A field strength-programming interface may show the extent to which anelectromagnetic field attributable to one stimulation zone overlaps withone or more additional electromagnetic fields attributable to one ormore additional stimulation zones. For instance, if unintended resultsare occurring for stimulation zones that have been programmed, anelectromagnetic-fields view provided by the field strength-programminginterface may indicate that the interaction between particularstimulation zones is causing the unintended results. The user mayinteract with user interface controls to reduce the interaction betweenthe stimulation zones.

An electrode-programming interface, in accordance with an illustrativeembodiment of the invention, may be at a level of abstraction lower thanthe stimulation zone-programming interface and the fieldstrength-programming interface. Users, who want to specify treatmentparameters by specifying electrode settings, may use theelectrode-programming interface. If desired, the user may then viewresulting electrical fields or current densities that will act onvarious portions of the stimulatable area by transitioning to a higherlevel of abstraction, such as the field strength-programming interface.

In accordance with an illustrative embodiment of the invention, for eachdisplayed pixel within a field-strength view's displayed stimulatablearea, the contribution from each modeled point charge may beindividually calculated and then added together. For each pixel ofinterest, a field strength may be calculated and then the pixel may beassigned a visual indication, such as a color, based on the calculatedfield strength.

When an idealized-stimulation-zone pattern is known, steps, inaccordance with an illustrative embodiment of the invention, may mapeither the stimulation zones view or the fields view to the electrodesview by generating electrode settings that approximate the knownstimulation-zones pattern. The stimulation zones may be mapped toelectrode settings via a successive-approximation technique. Startingwith a strongest stimulation zone and working to successively weakerstimulation zones, an electrode pair may be placed as close as possibleto the location of the corresponding stimulation zone.

In accordance with an illustrative embodiment of the invention, anelectromagnetic fields-view representation of stimulation zones may bemapped to an electrodes interface, when an electromagnetic-fieldsrepresentation is known, but a corresponding pattern of idealizedstimulation zones is unknown. An approximation of a set of idealizedstimulation zones may be generated via successive approximations thatwill attempt to approximate the known electromagnetic-fields pattern. Anarea, which has the highest intensity among areas not corresponding toan already-placed stimulation zone, is found and a stimulation zone isplaced at the found area. After placing a stimulation zone in thismanner, a field-strength pattern is calculated based on any stimulationzones that have already been placed. A determination is then made as towhether the calculated field pattern, which is based on the stimulationzones placed so far, is a sufficient approximation of the desiredfields. If the placed stimulation zones do not sufficiently approximatethe desired field-strength pattern, then an attempt is made to place atleast one additional stimulation zone in a similar manner.

Additional features and advantages of the invention will be apparentupon reviewing the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary operating environment for programmingneurostimulation-treatment parameters via a user interface in accordancewith an illustrative embodiment of the invention.

FIG. 2 depicts a stimulation zone-programming interface in accordancewith an illustrative embodiment of the invention.

FIG. 3 depicts a field strength-programming interface 300 in accordancewith an illustrative embodiment of the invention.

FIG. 4 depicts an electrode-programming interface 400 in accordance withan illustrative embodiment of the invention.

FIG. 5 is a flowchart depicting an overview of steps, in accordance withan illustrative embodiment of the invention, for programmingneurostimulation parameters via a user interface having three levels ofabstraction.

FIG. 6 is a flowchart depicting an overview of construction and displayof a stimulation zone-programming interface in accordance with anillustrative embodiment of the invention.

FIG. 7 depicts steps in accordance with an illustrative embodiment ofthe invention for constructing and displaying a stimulation fieldstrength-programming interface.

FIG. 8 depicts steps in accordance with an illustrative embodiment ofthe invention for moving from either the stimulation zones view or afields view to an electrodes view when an idealized-stimulation-zonepattern is known.

FIG. 9 depicts steps in accordance with an illustrative embodiment ofthe invention for transitioning from an electromagnetic fields-viewrepresentation of stimulation zones to an electrodes interface.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a general environment where a medical device such as anImplantable Pulse Generator (IPG) 5 may be used within a patient 6. TheIPG 5 may contain a power source and electronics to send precise,electrical pulses to the spinal cord, brain, or other neural tissue toprovide a desired treatment therapy. The IPG 5 may be powered by aninternal source such as a rechargeable or non-rechargeable battery or byan external source such as a radio frequency transmitter. The IPG 5 mayprovide electrical stimulation by way of electrical pulses. Other formsof stimulation, however, may be used such as continuous electricalstimulation.

The IPG 5 may use one or more leads 11A and 11B, and optionallyextensions 12A and 12B, for delivering therapy. The leads 11A and 11Bmay be surgically implanted within the patient 6. The leads 11A and 11Bmay be implanted and positioned to stimulate a specific site or area.The leads 11A and 11B may be positioned along a peripheral nerve,adjacent neural tissue, near muscle tissue or at other stimulation siteschosen by a clinician. The leads 11A and 11B contain one or moreelectrodes (small electrical contacts) 13A and 13B through whichelectrical stimulation may be delivered from the IPG 5 to the targetedneural tissue. The electrodes 13A and 13B may be arranged in apredetermined physical layout. For example, where there is more than oneelectrode, the electrodes may be arranged in a linear array, in multiplelinear arrays, or in a particular geometric array such as a triangle,square, rectangle, circle, etc. In addition, the IPG 5 may deliverstimulation therapy signals via the electrodes in a predetermineddirectional sequence based on the electrodes' physical layout in thestimulation area.

A programming device 14 may be used for programming various treatmentparameters of the therapeutic neurostimulation to be administered by theIPG 5. Data, such as the treatment parameters, may be transmitted fromthe programming device 14 via an RF link 16 to the IPG 5. Similarly,IPG-status information may be transmitted from the IPG 5 to theprogramming device 14 over the RF link 16.

In accordance with an illustrative embodiment of the invention and asdescribed in more detail below, a programming-device user interface mayinclude multiple levels of abstraction. A highest level of abstraction,referred to as a stimulation zone-programming interface, may showidealized stimulation zones. A middle level of abstraction, referred toas a field strength-programming interface, may show electromagneticfields generated by the stimulation zones, and/or electrode settings,and how these electromagnetic fields interact with each other. A lowestlevel of abstraction, referred to as an electrode-programming interface,may depict treatment settings at an electrodes-view level. Theseinterfaces may include a display of a stimulatable area of the patient'sbody. The various forms of this type of display may be referred toherein as a stimulation-zones view, a field-strength view, and anelectrodes view, respectively.

FIG. 2 depicts a stimulation zone-programming interface 200 inaccordance with an illustrative embodiment of the invention. This typeof interface is relatively simple to interact with and is at arelatively high level of abstraction in accordance with an illustrativeembodiment of the invention. The stimulation zone-programming interface200 lets a user work abstractly with idealized stimulation zones, suchas idealized stimulation zones 204-1 through 204-3. These stimulationzones are depicted with relative sizes corresponding to their respectiveintensities, namely, zone 204-1, with an intensity of 75%, isrepresented by a large circle; zone 204-2, with an intensity of 50%, isshown with a medium-sized circle; and zone 204-3, with an intensity of25% is shown with a small circle.

Initially, there may have been no active stimulation zones. A user, suchas a physician, may add a stimulation zone and may move the stimulationzone to a desired location. The user may adjust the stimulation zone'sparameters, such as its intensity, its pulse width, and its rate,example values of which are displayed in treatment parameter-displayarea 218. An indication 206 of which stimulation zone is currentlyselected for programming may be displayed. Zone-selection buttons 208-1through 208-3 may be provided for selecting a stimulation zone 204 forprogramming.

A display area 202 of the stimulation zone-programming user interface200 represents a stimulatable area within the patient's body, which isan area in which implanted stimulation leads are able to producestimulation. Two leads are often implanted parallel to one anotherabove, and parallel to, a patient's spine. Referring to FIG. 2, a firstlead and a second lead correspond to the left and right edges 232-1 and232-2 of the displayed stimulatable area such that stimulation zones maybe placed within in the display area 202. Before creating idealizedstimulation zones, a user may enter information specifying where, withina patient's body, one or more leads are placed, such as where the leadsare located relative to specific portions of the patient's spine. Thistype of lead-location information may also be made available by anyother suitable technique, such as the programming device 14 querying theIPG 5 for lead-location information.

Idealized stimulation zones may be placed relative to placement of theleads. A common configuration for implanted leads is two leads each withfour electrodes in parallel forming a rectangle. The stimulation zonestypically will fall somewhere within that rectangle. Using astimulation-zones view 200, a user may place idealized stimulation zones204 and configure stimulation parameters such as stimulation-zoneintensity. For instance, the user may put a higher intensity stimulationzone, such as stimulation zone 204-1, in the upper left hand portion anda lower intensity stimulation zone, such as idealized stimulation zone204-2, lower and to the right.

An image 212 of the underlying physiology of the stimulatable area, suchas a portion of the patient's spine, may be displayed based on thelead-location information. The physician may then place stimulationzones relative to the depiction 212 of the stimulatable area'sunderlying physiology, such as a depiction of the patient's spine.

After programming a first stimulation zone, the physician may add one ormore additional stimulation zones and may move the stimulation zones todesired locations. For instance, if a first stimulation zone isproviding effective pain relief for leg pain and the patient also hasarm pain, a second stimulation zone may be added to treat the patient'sarm pain. The stimulation zones may be placed in accordance withknowledge of where the nerves, which lead to the arms and legs, come outof the spine. Stimulation zones may be selected, moved, and removed asdesired.

Stimulation zones may be placed at predefined locations within thedisplay area 202, such as at an intersection of a horizontal grid line214 and a vertical grid line 216. Intersections of this type maycorrespond to electrode locations and locations substantially centrallylocated between an electrode on a first lead and an electrode on asecond lead.

In the lower portion of the stimulation zone-programming interface 200shown in FIG. 2, the treatment-parameter display area 218 depicts aname, rate, pulse width and intensity of a selected stimulation zone204. Below the treatment-parameter display area 218 are buttons 220through 228 and a status bar 230. The buttons may be used for adding(220) or removing (222) a stimulation zone. The update button 224 may beused for transferring programmed settings to the IPG 5. The more-detailbutton 226 may be used for transitioning from one level of abstraction,such as the stimulation zone-programming interface 200, to a differentlevel of abstraction, such as the field strength-programming interface300 (FIG. 3) or the electrode programming-interface 400 (FIG. 4).

FIG. 3 depicts a field strength-programming interface 300 in accordancewith an illustrative embodiment of the invention. This type of interfaceis, in accordance with an illustrative embodiment of the invention, at alevel of abstraction lower than the stimulation zone-programminginterface 200 (FIG. 2) and at a level higher than theelectrode-programming interface 400 (FIG. 4). For a user who iscomfortable thinking about electromagnetic fields directly, the user maypaint on the user interface what the user wants the field pattern tolook like. Darker colors may be used to represent more intensity, forinstance. While the field-strength view of FIG. 3 is less abstract thanthe idealized stimulation zones view of FIG. 2, the field-strength viewof FIG. 3 is more abstract than displaying which electrodes will beactivated in what manner on which leads to perform neurostimulation asdesired.

In accordance with an illustrative embodiment of the invention, afield-strength view 300 may depict a polarity or direction for variousdisplayed electromagnetic fields. An electromagnetic field may bedisplayed as a vector having a direction and a magnitude. A user maythen adjust not only the magnitude, but also the direction of anelectromagnetic field being displayed as a vector.

A field strength-programming interface 300 may show the extent to whichan electromagnetic field attributable to one stimulation zone overlapswith one or more additional electromagnetic fields attributable to oneor more additional stimulation zones. For instance, if unintendedresults are occurring for stimulation zones that have been programmed,an electromagnetic-fields view provided by the fieldstrength-programming interface 300 may indicate that the interactionbetween particular stimulation zones is causing the unintended results.The user may interact with the user interface controls shown in FIG. 3in a manner similar to the manner discussed above in connection withFIG. 2. The primary difference is that the stimulation zones aredisplayed in the electromagnetic-fields view in FIG. 3 as opposed to theidealized-stimulation-zones view of FIG. 2. To reduce overlap of fields,as shown in FIG. 3, a user may reduce the intensity of, or move thelocation of, one or more of the stimulation zones 204.

In accordance with an illustrative embodiment of the invention, theshape of electromagnetic fields 302-1 and 302-2 corresponding to theidealized stimulation zones 204-1 through 204-3 is shown. The strengthof the displayed electromagnetic fields may be depicted by relativeshading or coloring of the displayed fields to indicate the relativestrength of the fields at various locations within the display area 202.

FIG. 4 depicts an electrode-programming interface 400 in accordance withan illustrative embodiment of the invention. This type of interface is,in accordance with an illustrative embodiment of the invention, at alevel of abstraction lower than the stimulation zone-programminginterface 200 (FIG. 2) and the field strength-programming interface 300(FIG. 3). Users who want to specify treatment parameters by specifyingelectrode settings may use the electrode-programming interface 400. Ifdesired, the user may then view resulting electrical fields or currentdensities that will act on various portions of the stimulatable area bytransitioning to a higher level of abstraction, such as the fieldstrength-programming interface 300.

Steps for generating, displaying, and using the stimulationzone-programming interface 200, the field strength-programming interface300, and the electrode programming interface 400 will now be discussedin connection with FIGS. 5-9.

FIG. 5 is a flowchart depicting an overview of steps, in accordance withan illustrative embodiment of the invention, for programmingneurostimulation parameters via a user interface having three levels ofabstraction. FIG. 5 depicts an overall task flow of a possibleprogramming session. Although FIG. 5 depicts a single iteration from ahighest level of abstraction to a lowest level of abstraction any numberof transitions from one level of abstraction to another level ofabstraction may be performed, as desired by a user.

As depicted at step 500, the programming device 14 and the IPG 5 maysynchronize their data. For instance, the programming device 14 mayquery the IPG 5 for the IPG's current settings. Different IPGs maydiffer in the size of their batteries, the number of electrodes, thenumber of leads, and the like.

As depicted at step 502, a determination is made regarding the type ofleads that are present and/or the kind of therapy that may be performed.A particular IPG 5 may be used for one or more therapies, such as paintherapy or deep brain stimulation. Data regarding the type of therapy tobe performed may be used in connection with displaying the underlyingphysiology of the intended stimulation area. For example, the image 212of the patient's spine shown in FIG. 2 may be appropriate for paintreatment, but not for deep brain stimulation. Similarly, differenttypes of leads may vary in the number of electrodes, the spacing ofelectrodes, and/or the arrangement of electrodes, such as paddle leadsthat are smaller and wider than typical leads. Thiselectrode-configuration information may be used in connection withdisplaying an image the leads, such as the lead images 404-1 and 404-2shown in FIG. 4.

Configuration information of the type discussed in the immediatelypreceding paragraph may be queried via telemetry from various types ofIPGs 5. Alternatively, this kind of information may be input by a user.

A user may then input lead-location information, as depicted at step504. For instance, the user could indicate that a lead is implanted atthe tip of T7 (i.e., the seventh thoracic vertebra). Or the user mayindicate that the lead is located in some structure of the brain. Thisinformation may be used in connection with graphically displaying leadssuperimposed over the stimulation area's underlying physiology. A usermay input lead location information by entering a textual description ofone or more lead locations. The user could also drag-and-drop a graphicof the lead on to a graphic of the stimulation area, such as a portionof the patient's spine or brain to indicate the lead locationgraphically. Lead placement relative to the spine may be used forspecifying where pain treatment will be directed. For instance, arm painand leg pain maybe treated with leads located in different areas of thespine where nerves exit the spine and lead to these respective bodyparts.

As depicted at step 506, a stimulation-zones view may be displayed basedon the information discussed above in connection with steps 500-504. Forinstance, as part of displaying a stimulation-zones view, the followinginformation may be taken into consideration: the capabilities of thestimulator, the type of lead or leads, the type of therapy, and thephysiological location of the lead. Based on this type of information, astimulation-zones view, such as the one shown in FIG. 2, may beconstructed and displayed.

A user may then create, specify parameters for, move, and/or deleteidealized stimulation zones, as depicted at step 508.

If the user gets satisfactory results at this relatively high level ofabstraction, then programming the IPG 5 is complete for the desiredtreatment, as depicted by following the “yes” branch from step 510 tostep 520. If the user does not achieve satisfactory results at thislevel of abstraction, then the user may go a lower level of abstractionwithin the user interface, such as an electromagnetic-fields view, likethe one shown in FIG. 3.

“Satisfactory results” in step 510 may refer to a subjective indicationfrom the patient. In other words, a qualitative response about theeffectiveness of the treatment. The physician may change variousstimulation parameters and get feedback from the patient about whetherthe change improved the effectiveness of the treatment. For instance,the patient might indicate the degree to which pain or any othersymptoms are diminished.

As depicted at steps 512 and 514, an electromagnetic-fields view may beconstructed, and the user may program various treatment parameters fromthe electromagnetic-fields view. Step 512 refers to displaying a viewsuch as the electromagnetic-fields view shown in FIG. 3. This type ofview may show the extent to which a particular stimulation zone overlapswith one or more additional stimulation zones.

To reduce overlap of fields, as shown in FIG. 3, a user could reduce theintensity of one or more of the stimulation zones. There are also otherways to reduce the overlap of fields. For instance, a user could placean electrode with a negative polarity very close to a positive electrodeso that the resulting field would be constrained around those twoelectrodes. So, instead of creating each zone with a single electrode, auser could set up stimulation zones with two or more electrodes. Forinstance, a plus-minus-plus triplet or a minus-plus-minus arrangement,which is called a guarded cathode, may be used. Electrodes near aparticular electrode may be used to control the manner in which electricfields emanate from the electrode. The lowest level of abstraction, suchas the electrodes view of FIG. 4, allows a user to program settings forindividual electrodes in this way.

If the user gets satisfactory results at the electromagnetic-fields-viewlevel of abstraction, then programming the IPG is complete for thedesired treatment, as depicted by steps 516 and 520. If the user doesnot achieve satisfactory results at this level of abstraction, then, asdepicted at step 518, the user may go to a lower level of abstractionwithin the user interface, such as an electrodes view, like the oneshown in FIG. 4. If satisfactory results are not achieved at theelectrodes-view level, then the user may iterate to another level,remove and/or reposition one or more of the leads, and/or make otherchanges to the system, as appropriate.

FIG. 6 is a flowchart depicting an overview of construction and displayof a stimulation zone-programming interface in accordance with anillustrative embodiment of the invention. Step 600 corresponds to steps500-504 of FIG. 5. As mentioned previously, the programming device 14may query the IPG 5 for information, such as the number of leads, or auser may enter this type of information as input.

A visual indication may be displayed for indicating distinct positionsat which a user may position idealized stimulation zones. For instance,as depicted at steps 602-606, a grid of vertical and horizontal linesmay be drawn on the programming device's display area 202. A verticalline 216 may be drawn substantially over each lead and halfway betweenadjacent pairs of leads. A horizontal line 214 may be drawn for eachelectrode. The vertical grid line 234 (FIG. 2) between the electrodes,drawn by step 604, provides a user the option of placing stimulationzones between the leads. For instance, idealized stimulation zone 204-1could be moved one grid space to the right of its location in FIG. 2 sothat the stimulation zone 204-1 was then located on vertical grid line234. This could be achieved at the electrode-programming level,discussed below, by activating a top most electrode on both leadscorresponding to the left and right edges 232-1 and 232-2 of thedisplayed stimulatable area 202. The resulting field would then besubstantially centered between these two electrodes, thereby producing anet result of stimulation in the middle between the electrodes.

In an ideal case, there is a virtually unlimited number of electrodes ona lead, and stimulation zones may be placed in virtually any positionwithin the displayed stimulatable area 202. Conventional leads, however,typically have four or eight electrodes. Accordingly, the resolution ofthe electrodes effectively places a practical limit on where idealizedstimulation zones may be located. Therefore, rather than allowing a userto place a stimulation zone wherever the user wants to, and thenrequiring the user interface to move the arbitrarily placed stimulationzone to the nearest grid location, the user interface may use the gridto indicate to the user where the stimulation-zones may be located. Useof a grid in this manner may advantageously allow a user to avoidconfusion associated with stimulation zones being repositioned withoutthe user's knowledge. Using discrete stimulation-zone locations in thismanner also advantageously simplifies the steps performed by the userinterface for transitioning from one level of abstraction to a differentlevel of abstraction.

An image of the stimulatable area's underlying physiology, such as animage of a portion of a person's spine, may be depicted, as shown atstep 610. Selection of an image to be displayed may be based onavailable lead-location information.

FIG. 7 depicts steps in accordance with an illustrative embodiment ofthe invention for constructing and displaying a stimulation fieldstrength-programming interface 300. The steps in FIG. 7 relate totransitioning from a stimulation-zone interface 200 to a field-strengthinterface 300. As depicted at step 700, an electromagnetic-fieldstrength for each stimulation zone is modeled as a respective pointcharge, which is an approximation technique. Alternatively, a finiteelement analysis could be done. Analytic approaches tend to lead tocylinders of charge. As the number of electrodes to be modeledincreases, this type of approach tends to become relatively complex.Modeling the field strength as point charges provides a relativelyaccurate approximation and the computational complexity is reduced sothat a processor may execute the computations more quickly. In additionto finite element analysis, other analytical approaches may includecalculating voltages and/or current densities.

At step 702, the modeled point charges are scaled according to thestimulation zones' respective intensities. At step 704, anelectromagnetic field is calculated for a desired set of points within awindow of interest, which may be the displayed stimulatable area 202.For each displayed pixel within the displayed stimulatable area, thecontribution from each modeled point charge may be individuallycalculated and then added together. There is an inverse-squaredrelationship between the distance from a point charge and the strengthof the electromagnetic field attributable to the point charge. So, forexample, as a reference distance is tripled, the strength of theelectromagnetic field will reduce by a factor of 9, which is 3 squared.

The algebraic expression in step 704 may be evaluated pixel-by-pixel foreach pixel within the displayed stimulatable area. Or this calculationmay be performed for any other desired set of points, such as a subsetof the pixels within the displayed stimulatable area. For each pixel ofinterest, a field strength may be calculated and then the pixel may beassigned a visual indication, such as a color, based on the calculatedfield strength.

On the left the algebraic expression in step 704, is the net fieldstrength E(r) for a pixel at location r, which may be some x-y pixellocation. The first term to the right of the equal sign comprises 3constants and is, therefore, itself a constant. Stated differently, theinverse of four times E₀ times π is a constant. E₀ is the permativity offree space, which relates to the speed at which light travels in avacuum. E₀ may be varied depending upon the type of material in whichthe leads have been implanted. Evaluation of the expression proceedscharge-by-charge with Q1/R1 ². Q1 is the charge that a first electrodeis modeled with. So Q1/R1 ² represents a point charge located at aspecific pixel location away from where the first electrode is locatedon the lead, for instance. Q1 may be scaled based on the intensity ofthe first stimulation zone or electrode being modeled. R1 represents thedistance between the point charge being modeled and the current pixel'slocation. R may be a distance measured in pixels or some other unit oflength. So, the further away the pixel is from the electrode beingmodeled as a point charge, the weaker the electrode's contribution willbe to the net field strength at the pixel.

For a particular pixel, each electrode's contribution to the fieldstrength for that pixel is calculated. For instance, Q2/R2 ² mayrepresent a second electrode's contribution to the net field strength atthe current pixel. For any given calculation, a lot of the electrodeswill typically be off so that their Q values will be zero. As indicatedin the equation of step 704, the Q/R² contribution of each electrode issummed to produce a net field strength for a particular displayed pixel.

Steps 706-712 are similar to steps 608-614 described above. Iflead-location information is unavailable, for instance, because the userhas not entered any or the lead is nonstandard, then stimulationprogramming may begin, as depicted at step 712, without displaying adepiction of the underlying physiology of the stimulatable area.

FIG. 8 depicts steps in accordance with an illustrative embodiment ofthe invention for moving from either the stimulation zones view of FIG.2 or the fields view of FIG. 3 to the electrodes view of FIG. 4 when anidealized-stimulation-zone pattern is known. In light of the knowncapabilities of the IPG 5 and any available lead-configurationinformation, FIG. 8 sets forth steps in accordance with an illustrativeembodiment of the invention for generating electrode settings thatapproximate the known stimulation zones.

To map stimulation zones to electrodes settings, equations for anarbitrary number of electrodes may be written and solved. This type ofapproach involves relatively complicated calculations. A relativelysimpler approach, in accordance with an illustrative embodiment of theinvention, essentially approximates what the electrode setting should befor a particular pattern of stimulation zones.

FIG. 8 depicts steps in accordance with an illustrative embodiment ofthe invention for mapping stimulation zones to electrodes settings viaan approach of successive approximations. In general, a stimulation zonecomprises two electrodes, a positive cathode and a negative anode.Accordingly, the steps in FIG. 8 place an electrode pair of this typefor each stimulation zone. If a stimulation zone is located over onelead, then both electrodes of an electrode pair are placed on that lead.For instance, the two electrodes closest to the stimulation zone, whichhave not already been activated, may be activated, with one positive andone negative, to generate stimulation corresponding to the stimulationzone. A slightly more difficult case is when the stimulation zone islocated between the leads. An electrode on a first lead and an electrodeon a second lead may then be used to produce a stimulation zone betweenthe leads.

Starting with a strongest stimulation zone first, as depicted at steps800-808, a first electrode-pair is generated to produce stimulationapproximating the strongest stimulation zone. The first electrode pairmay be on a single lead (step 806) or may span two leads (step 804).Whether an electrode pair to be activated will be placed on one lead oracross multiple leads may depend upon whether the stimulation zone islocated more toward the left, toward the right, or in the center of thedisplayed stimulatable area 202. The first electrode pair may be set toa midrange voltage and/or may be scaled in accordance the stimulationzone's intensity, as depicted at step 808.

At step 810, a determination is made with respect to whether there areany other stimulation zones to be placed. If there are additionalstimulation zones, then the next strongest stimulation zone is placed byiterating through steps 800-808 again. During any subsequent iterationof these steps, electrodes, which have not already been activated, maybe activated to produce stimulation corresponding to the stimulationzone currently being placed without taking into account any interactionbetween previously activated electrodes and the electrodes currentlybeing activated.

Steps 812-818 are similar to 706-712 and 608-614 described above. Iflead-location information is unavailable, then stimulation programming,via manipulation of electrode settings, may begin, as depicted at step816, without displaying a depiction of the underlying physiology of thestimulatable area.

FIG. 9 shows steps in accordance with an illustrative embodiment of theinvention for transitioning from an electromagnetic fields-viewrepresentation 300 of stimulation zones to an electrodes interface 400.The steps shown in FIG. 9 may be used, when an electromagnetic-fieldsrepresentation is known, but a corresponding pattern of idealizedstimulation zones is unknown. So, for instance, if a user defineselectromagnetic fields initially without defining stimulation zones, orif a user makes significant changes, through the fields-view interface300, to previously defined stimulation zones, the steps of FIG. 9 may beused to generate an approximation of a set of idealized stimulationzones that will produce the known electromagnetic-fields pattern.

FIG. 9 sets forth steps for generating a set of idealized stimulationzones via successive approximations. The steps in FIG. 9 find an area,which has the highest intensity among areas not corresponding to analready-placed stimulation zone, and place a stimulation zone in thefound area, as depicted at steps 900 and 902. After placing astimulation zone in this manner and as depicted at step 904, afield-strength pattern is calculated based on any stimulation zones thathave already been placed. Step 904 may be performed in a manner similarto the field-strength calculations described above in connection withsteps 700-704 of FIG. 7.

Step 906 is essentially a metric for comparing how similar one fieldpattern is to another field pattern. If a calculated field pattern,which is based on the stimulation zones placed so far, is a sufficientapproximation of the desired fields, then no more stimulation zones areplaced, and an electrode interface 400 may be constructed and displayed,as depicted at step 910, using the stimulation zones placed in steps900-906.

Otherwise, if any additional stimulation zones may be placed, then steps908 and 900-906 are repeated for placing a next stimulation zone 204.The quality metric of step 906 may be weighted so that stronger areas ofstimulation are given more importance by the quality metric. In thisway, if the placed stimulation zones re-create the relatively strongerportions of the desired electromagnetic-field pattern, then the qualitymetric essentially doesn't care about the remaining relativelylower-intensity areas of the desired electromagnetic-field pattern. Atsteps 906, 908 and 912, if the calculated fields are an insufficientapproximation of the desired fields and no more stimulation zones areavailable for placement, then an indication is provided to notify theuser that the desired field pattern can not be reproduced with the IPG'scurrent lead and electrode configuration.

The steps set forth in FIG. 9 will essentially generate idealizedstimulation zones 204 based on a given pattern of desiredelectromagnetic-field strengths. The resulting stimulation zones 204 maythen be used for constructing a stimulation-zones view 200 and/or anelectrodes view 400.

What has been described above is merely illustrative of the applicationof the principles of the present invention. The invention shouldtherefore be limited only by the claims below. Any of the methods of theinvention may be implemented in software that may be stored on computerdisks or other computer-readable media.

1. A method comprising: representing an anatomical region on a display;representing an electrical stimulation lead on the display; receivingdirectional user input specifying movement of the lead relative to theanatomical region; moving the representation of the lead on the displayto a position in response to the directional user input; receiving userinput specifying one or more stimulation parameters associated withstimulation therapy applied by an electrical stimulator via the lead;and representing a stimulation field produced by the lead based on theposition of the lead and the specified stimulation parameters.
 2. Themethod of claim 1, wherein the directional user input includesdrag-and-drop movement of the lead.
 3. The method of claim 1, whereinrepresenting a stimulation field includes representing at least oneidealized stimulation zone on the display.
 4. The method of claim 1,wherein representing a stimulation field includes representing anelectromagnetic field strength corresponding to an idealized stimulationzone on the display.
 5. The method of claim 1, further comprisingmodifying the representation of the stimulation field in response touser input.
 6. The method of claim 1, wherein the anatomical regionincludes a brain.
 7. The method of claim 1, wherein the anatomicalregion includes a spine.
 8. The method of claim 1, further comprising:representing the stimulation field on the display as an idealizedstimulation zone at a first level of abstraction of a user interface;permitting the user to specify the stimulation parameters bymodification of the idealized stimulation zone; representing thestimulation field as an electromagnetic field strength at a second levelof abstraction of the user interface lower than the first level ofabstraction; permitting the user to specify the stimulation parametersby modification of the electromagnetic field strength; presenting anelectrode programming interface at a third level of abstraction of theuser interface lower than the second level of abstraction; andpermitting the user to specify the stimulation parameters by interactionwith the electrode programming interface.
 9. The method of claim 1,wherein the electrical stimulator is an implantable electricalstimulator.
 10. A programming device for an electrical stimulator, thedevice comprising: a display that displays a representation of ananatomical region, and a representation of an electrical stimulationlead; and a user input interface that receives directional user inputspecifying movement of the lead relative to the anatomical region, andreceives user input specifying one or more stimulation parametersassociated with stimulation therapy applied by an electrical stimulatorvia the lead, wherein the display moves the representation of the leadin response to the user input, and displays a representation of astimulation field produced by the lead based on the position of the leadand the specified stimulation parameters.
 11. The device of claim 10,wherein the directional user input includes drag-and-drop movement ofthe lead.
 12. The device of claim 10, wherein the display represents thestimulation field as an idealized stimulation zone.
 13. The device ofclaim 10, wherein the display represents the stimulation field as anelectromagnetic field strength corresponding to an idealized stimulationzone.
 14. The device of claim 10, wherein the display modifies therepresentation of the stimulation field in response to user input. 15.The device of claim 10, wherein the anatomical region includes a brain.16. The device of claim 10, wherein the anatomical region includes aspine.
 17. The device of claim 10, wherein the display represents thestimulation field as an idealized stimulation zone at a first level ofabstraction of a user interface, represents the stimulation field as anelectromagnetic field strength at a second level of abstraction of theuser interface lower than the first level of abstraction, and presentsan electrode programming interface at a third level of abstraction ofthe user interface lower than the second level of abstraction, andwherein the user input interface permits the user to specify thestimulation parameters by modification of the idealized stimulationzone, permits the user to specify the stimulation parameters bymodification of the stimulation field, and permits the user to specifythe stimulation parameters by interaction with the electrode programminginterface.
 18. The device of claim 10, wherein the electrical stimulatoris an implantable electrical stimulator.
 19. A computer-readable mediumcomprising instructions to cause a processor to: represent an anatomicalregion on a display; represent an electrical stimulation lead on thedisplay; receive directional user input specifying movement of the leadrelative to the anatomical region; move the representation of the leadon the display in response to the directional user input; receive userinput specifying one or more stimulation parameters associated withstimulation therapy applied by an electrical stimulator via the lead;and represent a stimulation field produced by the lead based on theposition of the lead and the specified stimulation parameters.
 20. Thecomputer-readable medium of claim 19, wherein the directional user inputincludes drag-and-drop movement of the lead.
 21. The computer-readablemedium of claim 19, wherein the instructions cause the processor torepresent at least one idealized stimulation zone on the display. 22.The computer-readable medium of claim 19, wherein the instructions causethe processor to represent an electromagnetic field strengthcorresponding to an idealized stimulation zone on the display.
 23. Thecomputer-readable medium of claim 19, wherein the instructions cause theprocessor to modify the representation of the stimulation field inresponse to user input. 24 The computer-readable medium of claim 19,wherein the anatomical region includes a brain or a spine.
 25. Thecomputer-readable medium of claim 19, wherein the instructions cause theprocessor to: represent the stimulation field on the display as anidealized stimulation zone at a first level of abstraction of a userinterface; permit the user to specify the stimulation parameters bymodification of the idealized stimulation zone; represent thestimulation field as an electromagnetic field strength at a second levelof abstraction of the user interface lower than the first level ofabstraction; permit the user to specify the stimulation parameters bymodification of the electromagnetic field strength; present an electrodeprogramming interface at a third level of abstraction of the userinterface lower than the second level of abstraction; and permit theuser to specify the stimulation parameters by interaction with theelectrode programming interface.
 26. The computer-readable medium ofclaim 45, wherein the electrical stimulator is an implantable electricalstimulator.